Preparation And Properties Of CeO₂ And Re₂O₃ Co-Stabilized ZrO₂ Thermal Barrier Coating Materials

6-8 wt.%Y₂O₃ partially stabilized ZrO₂（6-8 YSZ）thermal barrier coatings（TBCs）have been widely used on the surfaces of high-temperature components such as gas turbine engines,providing thermal protection for high-temperature components,thereby improving the thermal efficiency of the engine and extending the service life of high-temperature components.However,YSZ coating is subject to phase transformation and sintering,at operating temperatures above 1200℃,leading to premature failure and spalling of the coating.Therefore,it is necessary to develop TBCs materials that are capable of long-term stability at high-temperature（>1200℃）and have good thermal insulation property.In this study,16 mol%Ce O₂ and 2 mol%Re₂O₃ co-doped stable Zr O₂ materials(Ce_0.16Re_0.04Zr_0.80O_1.98,16Ce4ReSZ,Re=Eu,Gd,Dy,Y,Er,Yb)were prepared by chemical coprecipitation–high-temperature roasting and high-temperature solid-state synthesis.The high-temperature phase stability,mechanical properties,thermal physical properties and sintering resistance of 16Ce4Re SZ materials were investigated.16Ce4Yb SZ powder was selected to prepare the coating.The microstructure,high-temperature phase stability,mechanical properties,thermophysical properties and thermal cycling property of the coating was investigated.In addition,the corrosion resistance of 16Ce4Yb SZ and YSZ materials to CMAS was investigated.The main research conclusions are as follows:（1）The phase stability of 16Ce4ReSZ（Re=Eu,Gd,Dy,Y,Er）powder at 1400℃ was investigated.It was found that the phase stability of 16Ce4Re SZ increased with the decrease of Re³⁺radius,among which 16Ce4Yb SZ had the best phase stability.16Ce4Re SZ（Re=Dy,Y,Er,Yb）with relatively good stability were selected to test the mechanical properties,thermal conductivity,thermal expansion coefficient and sintering resistance.With the decrease of Re³⁺radius,hardness,fracture toughness and Young’s modulus decreased,thermal conductivity increased,thermal expansion coefficient and sintering resistance decreased.The thermal conductivity of 16Ce4Re SZ（Re=Dy,Y,Er,Yb）materials were lower than YSZ,and its thermal expansion coefficient,mechanical properties,and sintering resistance were better than YSZ.（2）Based on the last work,16Ce4YbSZ material was selected to prepare the coating.The 16Ce4Yb SZ coating was prepared by atmospheric plasma spraying（APS）.Typical layered structure,pores and microcracks in the 16Ce4Yb SZ coating were observed.After heat treatment at 1400℃,part of tetragonal phase（t）was transformed into c phase,m-phase was not observed in 16Ce4Yb SZ coating.The 16Ce4Yb SZ showed relatively good stability.The mechanical properties of 16Ce4Yb SZ coating were similar to YSZ,thermal conductivity was lower than YSZ,the thermal expansion coefficient was higher than YSZ.16Ce4Yb SZ/YSZ TBCs exhibited longer thermal cycle lives than 16Ce4Yb SZ TBCs at 1050℃ due to the buffering effect of the YSZ layer.The causes of coating failure were thermally grown oxide（TGO）growth,thermal expansion mismatch and coating sintering.（3）In CMAS isothermal corrosion test,the corrosion degree,penetration depth,and corrosion mechanism of 16Ce4Yb SZ and YSZ materials were investigated at 1250℃ for1 h,5 h,and 10 h.The wettability of CMAS on the surfaces of the two materials was also investigated.The results showed that the CMAS corrosion resistance of 16Ce4Yb SZ material was superior to YSZ.The corrosion degree,penetration depth,and surface wettability of CMAS on YSZ material were higher than 16Ce4Yb SZ material.The stabilizer Y³⁺in YSZ had a high affinity with CMAS,and it was easier to precipitate out of the Zr O₂ crystal and dissolve in CMAS.Ca²⁺and Mg²⁺in CMAS also diffused into Zr O₂ crystal,promoted segregation of the stabilizer in t-Zr O₂ crystal.c-Zr O₂ with high stabilizer content and m-ZrO₂ with low stabilizer content were generated.